Presently, heavy duty cargo trailers are typically built using four wheels that are placed together as close as possible to the trailer's center of gravity. This type of trailer is able to “seesaw” as the trailer remains in a reasonably balanced condition on the four wheels. This type of trailer can be seated on one axle where the position of the four wheels is determined along an arm that is perpendicular to the length of the trailer and measured such that the center of the wheels correspond to the center of gravity of the trailer. Also, two axles can be used. In this case, the wheels are mounted on a suspension system.
Both of these methods of construction have a fixed height and it is not possible to load them without elevating the load by using another system.
Consequently, there is not found in the prior art a trailer such that the trailer can be lowered to facilitate loading and unloading.